A number of solar energy conversion methods and related technologies have now been integrated into the mix of large-scale energy production systems in many parts of the world. Systems and processes are known that convert sunlight directly to electricity via arrays of photovoltaic panels.
The majority of deployed photovoltaic systems are based on silicon semiconductor material, the native properties of which, combined with some engineering related issues, have constrained the achievable solar-to-electric energy conversion efficiency in production grade panels to a maximum of about 20%. A theoretical maximum for silicon-based solar cells of about 33.7% has been predicated; this is known as the Shockley-Queisser detailed balance limit [W. Shockley and H. J. Queisser, “Detailed balance limit of efficiency of p-n-junction solar cells,” J. Appl. Phys. 32 pp. 510-519 (1961)]. An immediate consequence of the conversion efficiency constraint on production grade panels is the necessity to cover large areas of land or rooftops with silicon semiconductor material in order to achieve useful electric power generation capacities for individual households; this, in turn, means much larger land areas must be covered with silicon for utility-scale grid distribution.
All flat plate photovoltaic panels and concentrated photovoltaic systems installed today are made without provision for future upgrades to better panels or modules if such were to become available. Once installed, these systems are expected to be in service for 10 to 15 years. It is not expected that they would be upgradeable or replaceable if new, higher efficiency ones become available. There are economic and technical reasons for this. The most important are that (i) it would be expensive and therefore wasteful to replace some or all of the panels or modules, and (ii) it is simply not technically feasible with current design configurations for panels or modules.
With the current global push to derive more energy from renewable sources, new investments to improve photovoltaic technologies will be made. Inevitably, this will result in better devices and systems. It is therefore important that photovoltaic systems be designed with a provision for replaceable semiconductor devices that can be easily swapped out when better ones become available.
The relentless pursuit of perfection of photovoltaic devices requires that, whenever possible, power plants incorporating photovoltaic components be constructed in a manner that readily facilitates upgrading of the semiconductor components at reasonable cost. This is especially true since the infrastructure is generally expensive and expected to be in service for several decades.